title: Can urodynamic studies predict bladder behaviour changes after artificial urinary sphincter implantation?
abstract: OBJECTIVE
  To assess whether preoperative urodynamic studies can predict bladder behaviour changes that will necessitate bladder augmentation in patients with neuropathic incontinence after undergoing artificial urinary sphincter (AUS) implantation.
  
  
  METHODS
  We analysed 17 patients, with a mean age of 14.4 years at AUS implantation, who did not undergo bladder augmentation either before or at implantation. All patients were followed at regular intervals before and after implantation. Urodynamic studies were done at least three times before implantation and yearly thereafter. Bladder capacity and compliance were evaluated preoperatively and during the follow up, in order to determine whether these urodynamic measurements could predict the eventual need for bladder augmentation.
  
  
  RESULTS
  After a mean follow up of 7.5 years bladder behaviour was unchanged in 11 patients while six required augmentation. In these six patients, normal bladder capacity and compliance decreased from 67 to 39.6% of age expected capacity (AEC) (P=0.004) and from 31.6 to 13.5 ml/cm of water (P=0.001), respectively. Four of the six had no clinical symptoms to suggest the change in bladder behaviour. The differences in the average preoperative and follow up values for both normal bladder capacity (72.4 vs 83.5% of AEC) and compliance (30 vs 33.7 ml/cm of water) were not significant in the non-augmented patients (P=0.2 and P=0.3, respectively). Preoperative normal bladder capacity and compliance were 72% of AEC and 30 ml/cm of water, respectively, in the 11 non-augmented patients and 67% and 31 ml/cm of water in the six patients with augmentation. These differences between the two groups were not significant (P=0.06; P=0.1).
  
  
  CONCLUSIONS
  Preoperative urodynamic studies do not predict bladder function outcome after AUS implantation. These patients require long-term careful observation to detect any asymptomatic change in detrusor behaviour.
authors.affiliation: Department of Paediatric Urology, University Hospital La Paz, P degrees de la Castellana 261, Madrid 28046, Spain. plpuro@hotmail.com
authors.forename: P
authors.initials: P
authors.lastname: López Pereira
authors.forename: I
authors.initials: I
authors.lastname: Somoza
authors.forename: M J
authors.initials: MJ
authors.lastname: Martínez Urrutia
authors.forename: L
authors.initials: L
authors.lastname: Romera
authors.forename: E
authors.initials: E
authors.lastname: Jaureguizar